[Multibilly]

There's FISH and then there's selective FISH

by Multibilly on Wed Aug 26, 2015 5:39 pm

Watch this video.I had never considered the points these docs make about the importance of cell sorting in the context of FISH analysis. After reviewing my FISH report, I still have no idea if any cell sorting procedure was done on the portion of the aspirate used in the FISH analysis.Seems like folks ought to be proactively asking for this step when they get a bone marrow biopsy. Another thing for me to chat about with my onc when I see him next week

[TerryH]

Re: There's FISH and then there's selective FISH

by TerryH on Wed Aug 26, 2015 6:25 pm

Hi Multibilly,

I'm sure you've heard of this before. I think it's just the way it's described by the people on the panel versus the way you've seen it described before. Unless I'm misinterpreting the point you want to emphasize from the video, it's been brought up several times by the docs here in the forum. See the comments, for example, from Dr. Voorhees and Dr. Landau in this thread from last fall about the percentages in FISH results:

"Percentages in FISH test results - significance?" (started Oct 16, 2014)

There are other threads that discuss the issue as well -- for example, this one from 2011:

"Plasma cell percentage & speed of progression" (started Oct 21, 2011)

Again, maybe I'm not understanding what you're focusing on in the video. But if I understand you correctly, I think you've come across this before.

[Multibilly]

Re: There's FISH and then there's selective FISH

by Multibilly on Wed Aug 26, 2015 7:26 pm

Terry,

Perhaps I did come across this before, but I don't think Dr. Voorhees' comments in this thread you listed really stuck with me if I did read it before.

I think the important thing to determine is whether or not the plasma cells were isolated and purified prior to performing the FISH analysis. In other words, was the lab performing FISH on purified plasma cells or the entire white blood cell population in the bone marrow?

If the myeloma (plasma) cells were purified / enriched first and only 5% of the isolated plasma cells had the 17p deletion, this would be considered a better situation (although it would still mean that a small subpopulation of your disease harbors this abnormality). If the FISH was performed on the entire white blood cell fraction, it makes it difficult to know what percentage of plasma cells contain the 17p deletion. You can come up with an estimate based on the percentage of plasma cells in the bone marrow aspirate, but it is harder to use the data from the abstract you cited if the plasma cells were not purified."

Thanks for the links!

[JPC]

Re: There's FISH and then there's selective FISH

by JPC on Wed Aug 26, 2015 10:48 pm

Multibilly:

Thank you very much. You raised an important underlying issue. There is a standards problem with the FISH test that the "Powers that be" should be looking at. In our case, we were advised two contradictory results when we went for a second opinion at a second myeloma center. I wondered why this was the case, and did not have any real good idea until I read your post, which I think would explain the situation pretty clearly. Thank you.